Hello James,
Yes this is something that you can have a go at yourself!
It sounds like a possible scale issue - and as you still have (some!) water flow through the head, this makes it a bit easier.
Get some de-scaler product - I think you can pick some up at happydonkey.co.uk, although I was able to pick some up at my local kitchenware shop. Run that through your machine, it should improve your flow somewhat if it came from a hard water area. (you can also use lemon juice if you are pushed for product - I have done this before and was very happy!)
When you have the de-scaler fluid in the machine, be sure to run some through your steam wand.
If this fails, you may want to get further into the machine and look at this thread:
http://toomuchcoffee.com/index.php?name ... pic&t=8064
As for the steam wand, it may well be clogged up. Take off the black steam wand (the black collar at the top is threaded, undo the threaded collar and the steam wand should just slip off). Get a straightened paperclip or a pipe cleaner and clear the inside of the steam wand. Failing that, you can remove the steam wand - that's a little more involved - come back if it comes to this!! I hope the descale will sort both of these.
Good luck!!